This invention relates generally to ethynyl adamantane derivatives as new compositions of matter and to methods of synthesizing and polymerizing these compounds in formulations having useful commercial properties. At present, composite matrix resins, structural adhesives and surface films are used for a number of aerospace structural applications. Presently available materials for such purposes lack adequate stability and suitable physical properties for certain system design applications. Also, there is a need for improved polymers for use as matrices for carbon-carbon systems. For such applications, polymers compatible with carbon fibers which can be pyrolyzed to yield dense, coherent matrices are needed. Another need is for thermally stable polymers with low dielectric constants for electrical insulator usage.
One approach heretofore taken to obtain improved thermally stable polymers for the above-indicated purposes has involved the attachment of acetylene groups to stable organic structures and polymerization of the acetylenic structures by cyclotrimerization or other mechanisms. Stable linking groups have thus been formed without the polymerization of volatile by-products that would result in mechanical imperfections. Stable heterocycles, aromatic polyethers and similar materials have been linked in this manner. Still there has existed a need for significant improvement in such materials for the above-indicated applications. One such improvement was found in a high temperature thermoset resin obtained by the polymerization of 1,3-diethynyladamantane (DEA), as disclosed in U.S. Pat. No. 4,849,565, issued July 18, 1989, and assigned to the assignee of the present application. Curing of the DEA to the resulting polymer, we found, could be accomplished without a catalyst at 210.degree. C. or by using a metal catalyst at 180.degree. C. We further determined that the polymer showed no glass transition prior to the onset of major thermal decomposition in air at 476.degree. C. (by TGA analysis).